2018-02-16T12:26:26ZThe Causes and Consequences of Divergence Between the Air Traffic Controller State Awareness and Actual System Statehttp://hdl.handle.net/1721.1/111948
The Causes and Consequences of Divergence Between the Air Traffic Controller State Awareness and Actual System State
Abel, Brandon; Hansman, R. John
Divergence is an inconsistency between the human’s system state awareness and the actual system state. This research investigated divergence potential in air traffic controllers and identified controller divergence causes and consequences. Based on this investigation, approaches to minimize controller divergence and its consequences were identified for current air traffic control systems and future systems where unmanned aircraft will be integrated.
Prior studies identified pilot divergence as a factor in several recent aircraft accidents and could be a factor for controllers. The future addition of unmanned aircraft in national airspace is a significant change which will affect the pilot and controller relationship and presents an opportunity to consider divergence before procedures are developed.
To understand how to minimize divergence and its consequences, this research developed a divergence cause and consequence framework and a cognitive process framework. The cause and consequence framework was developed using established risk analysis methods. The cognitive process framework was developed using established cognitive process and human error approaches. This research refined these frameworks and demonstrated their utility in an investigation of historical air traffic control accidents. They were then used to identify divergence vulnerabilities in a future unmanned aircraft-integrated national airspace.
Air traffic control cases were analyzed between 2011 and 2015 using the framework to understand causes and consequences of controller divergence. Twenty-seven (sixty-four percent) of these cases contained controller divergence contributing to the hazardous consequence. Although divergence causes and states varied, the most common event sequence included a diverged controller inducing an aircraft-to-aircraft conflict. These cases provided insight for system mitigations to reduce divergence causes and the consequentiality should it occur.
The potential emergence of controller divergence with the integration of unmanned aircraft in national airspace was then investigated. Field studies of controllers experienced managing unmanned aircraft identified important differences between manned and unmanned aircraft. The framework was then used to analyze these potential divergence vulnerabilities. Observables, specifically intent, appear more challenging to perceive yet crucial for controller projection of unmanned aircraft position due to their lack of onboard human perception, lost link, and automated operations. Hazardous consequences may be more likely due to the inability for unmanned aircraft to provide mitigations.
2017-10-18T00:00:00ZComparison of Methods for Evaluating Impacts of Aviation Noise on Communitieshttp://hdl.handle.net/1721.1/110791
Comparison of Methods for Evaluating Impacts of Aviation Noise on Communities
Brenner, Morrisa A.; Hansman, R. John
Community opposition to the noise concentration from precise NextGen Performance-Based Navigation (PBN) aircraft arrival and departure procedures poses a significant threat to the future of these procedures in the U.S. National Airspace System. A substantial number of complaints concerning airport noise come from locations outside the 65dB Day-Night Level (DNL) contour considered the significant noise exposure threshold in U.S. federal regulation. This indicates that this threshold does not sufficiently capture areas that experience annoyance related to more concentrated, lower level overflight noise at distances farther from the airport. This thesis assesses the effectiveness by which different noise analysis methods capture the locations of these airport noise complaints through examination of the noise exposure for three representative scenarios at Boston Logan International Airport using DNL and number of overflights above a noise threshold (Nabove) metrics. The three scenarios examined include the standard noise analysis methodology scenario (annual average day) as well as a day of heavy usage of a noise-sensitive runway (33L for departures), and a scenario representing a peak hour of departures on this runway. The results indicate that the 33L peak day scenario does a better job of capturing a substantial fraction of the complainants sensitive to the 33L departure trajectories (66%-87% at the 45dB-50dB DNL thresholds) than the standard annual average day scenario. Results for the 33L peak day scenario indicate that the Nabove metric is also effective at capturing noise complaints at the 60dB day/50dB night noise threshold at exposure rates in the 25-50 overflight range (78%-84% complainant capture).
2017-07-20T00:00:00ZModeling the Effects of Aircraft Flight Track Variability on Community Noise Exposurehttp://hdl.handle.net/1721.1/110790
Modeling the Effects of Aircraft Flight Track Variability on Community Noise Exposure
Brooks, Callen; Hansman, R. John
The implementation of Performance Based Navigation (PBN) routes across the National Airspace System (NAS) has caused a significant concentration of flight tracks. This flight track concentration also creates a concentration of noise impacts on the communities surrounding airports, which has led to an increase in noise complaints at many airports that have implemented these routes. In order to understand these changes in noise, and to design procedures that could help mitigate any negative effects, it is important to have modeling tools capable of capturing the noise impacts of flight track variability. This thesis develops a model for this purpose. First, twenty days of radar flight trajectory data from 2015 and 2016 at Boston Logan International Airport (KBOS) is used to quantify the observed distributions of variability in speed, altitude, and lateral track position. It is shown that altitude and speed variability have relatively small impacts on noise, but that the impacts of observed lateral variability are significant. Using this information, a physics-based model is developed to capture the noise impacts of lateral flight track variability. This tool is then used to model several example scenarios. First, the changes in noise due to pre- and post-PBN procedures are examined for KBOS Runway 33L departures. Next, a hypothetical procedure is designed to intentionally introduce lateral dispersion to KBOS Runway 33L departures. Finally, the tool is used to rapidly model noise impacts on due to both arrival and departure operations on all runways at KBOS. The model is shown to reduce computational expense by 1-2 order of magnitude relative to traditional methods. The results of these example analyses show that increased lateral dispersion causes a significant noise reduction at higher noise levels directly below the flight track at the cost of wider contours at lower noise levels. Because of this, any decision to add or remove flight track lateral dispersion has highly localized impacts that depend on the geometry of the route and the population of the surrounding area, and thus must be closely analyzed on an individual basis.
2017-07-20T00:00:00ZAnalysis of Approach Stability and Challenges in Operational Implementation of RNP Approach Procedureshttp://hdl.handle.net/1721.1/109301
Analysis of Approach Stability and Challenges in Operational Implementation of RNP Approach Procedures
Salgueiro, Sandro
Required Navigation Performance (RNP) instrument procedures guarantee high levels of navigation precision through highly accurate navigation sources (e.g. GPS) and real-time monitoring of position estimation accuracy. In recent years, the Federal Aviation Administration (FAA) has developed and published public RNP approach procedures at airports across the country. These RNP procedures offer unique capabilities such as curved segments (radius-to-fix,
or RF legs), narrow containment areas, and constant descent profiles that are not seen combined in other categories of instrument approaches. Because of these capabilities, RNP approaches are regarded as highly flexible procedures that can be designed to meet specific stakeholder requirements (e.g. lower minimums in mountainous areas, minimizing fuel burn during approach, avoiding flight over populated areas for noise abatement, etc.) at the airport level. Among the various proposed benefits of RNP approaches, this study analyzed potential safety benefits related to improvements in approach stability. In total, 11,062 individual approaches at four airports were analyzed using radar (ASDE-X) data, of which 364 (3.29%) were identified as RNP procedures. Of all approaches analyzed, two non-RNP cases were identified as unsafe,
while there were no unsafe RNP cases. However, due to the relatively low number of RNP approaches observed, no statistically significant evidence of improved stability on RNP approaches was found. Given the low utilization of RNP approach procedures found from radar data, further work was done to identify barriers to operational use of these procedures and to investigate strategies to accelerate the adoption of RNP across the National Airspace System (NAS). Potential factors driving the low utilization of RNP procedures were found to be the low levels of equipage and operational approval among air carriers, and difficulties in air traffic management stemming from mixed equipage operations.
2017-05-23T00:00:00Z